A large volcanic centre (Myggbukta Complex) lies across the main dyke swarm in the vicinity of the deflection and may be genetically related to the swarm. The complex involves propylitized basaltic, rhyolitic and intermediate lavas and pyroclastic rocks, together with volcanogenic sediments, cut by a profusion of basic to acid intrusive sheets. Formation of this complex at a late stage in the volcanic history of the region was attended by subsidence and crustal down-sagging. The main dyke swarm, whose trend roughly parallels that of the spreading axes N and S of the Jan Mayen Fracture Zone, may reflect subordinate rifting to the W of the principal rift zones along which spreading was taking place.

30 km E of Myggbukta, the Kap Broer Ruys granophyre/felsite is a partially unroofed intrusion around which a broad metamorphic aureole has been superimposed on the Mesozoic and Tertiary sediments and lavas. The southern coastal region of Hold with Hope, connecting the Myggbukta and Kap Broer Ruys centres, may indicate a zone of crustal weakness which determined the initiation of the Jan Mayen Fracture Zone.